The invention relates to structures suitable for mobile carriages such as trailers, motor coaches and the like. The structure of this invention is especially useful for sidewalls of mobile carriages, however, it can be used for end walls, roofs, floors. It can also be used for making panels for structures that are prefabricated including prefabricated houses. This invention is also for a method of producing the structure of this invention. The method is especially useful for mass production of the structure in a production line assembly operation.